I excited my wife by suggesting we take a spare bedroom we never use and turn it into a big butlers pantry. Of course this went over well, who doesn't want 120 square foot pantry.
We are using white Pine pre sanded plywood cut into squares then we sand the hell out of it more starting with 60 grit and ending with 320 grit. Then stain it and polyurethane clear coat. MANY coats.
Johnny came in to help but then left when the sander started up again.

Why not lay the wood in the full sheets rather than squares?FRemember in shop class me and another student were tasked in building a portable dance floor.Used plywood-two sheets per "unit" trying to remember the number of sections we made-it was a very large floor.Sanding took the most time-laying down and sanding as you are in the picture--then got the idea of letting the oscillating sander go on its own-was able to work on other projects this way-worked GREAT!!Was weird to watch--the sanding machine would go in random directions-but would still sand the whole section without further help.Just had to change the sandpaper occasionally-and change grits.Don't know if the method I mentioned would work with your sander-the ones we used were Rockwell rectangular half sheet oscillating machines.

I think if they were going to go with just plywood as the main floor covering, the squares are much better way to go. It gives it more of a pattern and personality, makes a small space look bigger, and just makes it look like more thought and work went into it. I would go with a darker stain to disguise the fact that it's subfloor material, but it could look great. Now all it needs are custom upper and lower cabinets surrounding the edges of the room with a wine cooler maybe? Haha. But that's just my purely unprofessional opinion as an Interior Designer.